Receivers must be capable of receiving a signal of varied strength. When testing a receiver, it is common to use a signal generator to generate a signal of the desired frequency to be tested. The signal generator will typically generate a signal of a given strength. The signal is then fed into an attenuator where the operator attenuates the signal to the desired level to input into the receiver for testing.
A variety of attenuators are known. The attenuator can be a simple manually operated attenuator where the operator moves a switch to different attenuation steps. Other attenuators are electronically operated by a control voltage set between certain limits controlling the degree of attenuation.
In addition to sensitivity, a receiver also must be capable of adjusting gain as the input signal varies strength. A characteristic of the receiver known as the slew rate indicates how quickly the receiver can vary gain with a variation in the input signal strength. It is necessary to test the receiver to determine if the receiver is capable of varying gain at the rated slew rate.